mfn2基因转染对非酒精性脂肪肝细胞线粒体功能的影响

目的:研究线粒体融合蛋白基因2(mfn2)对非酒精性脂肪肝细胞线粒功能的影响。方法:利用脂质体lipofectamine2000将mfn2基因荧光表达载体(pEGFP-mfn2)转染肝细胞株L02,并采用油酸诱导L02建立非酒精性脂肪性肝细胞模型,RT-PCR及Western blotting检测细胞mfn2mRNA和蛋白的表达;荧光素酶ADP/ATP发光法检测各组细胞内ATP水平,荧光探针DCFH-DA测定细胞活性氧(ROS)生成水平;JC-1标记细胞线粒体,流式细胞仪检测线粒体跨膜电位(Δψm)的变化。结果:转染mfn2基因的L02可以稳定高表达mfn2mRNA及蛋白,转染后L02内ATP浓度及线粒体跨膜电位显著升高(P0.05),而ROS生成水平则显著下降(P0.05);经油酸诱导肝细胞脂肪变性后,L02mfn2表达受抑制,各组细胞内ATP浓度及线粒体跨膜电位均显著下降(P0.01),而ROS生成水平较前均显著升高(P0.01),但转染组细胞内ATP下降水平以及线粒体跨膜电位下降幅度均显著低于未转染组,而未转染组ROS升高程度则显著高于转染组(P0.01)。结论:外源性mfn2基因转染可以抑制油酸诱导的肝细胞内ATP浓度和线粒体跨膜电位的下降以及ROS生成的增加。     

槲皮素抑制异烟肼诱导的L-02细胞线粒体氧化应激性DNA损伤

目的:探讨活性氧(ROS)介导的线粒体氧化损伤在异烟肼(INH)诱导L-02细胞DNA损伤中的作用及槲皮素对细胞的保护作用。方法:建立体外培养INH致肝细胞L-02损伤的模型,将细胞分为对照(control)组、INH组、槲皮素低剂量(Que low)及高剂量(Que high)组。利用彗星试验评价细胞DNA损伤;制备L-02细胞线粒体,应用荧光探针DCFH-DA和rhodamine 123检测细胞线粒体ROS水平及线粒体膜电位(ΔΨm);采用TBA法测定丙二醛(MDA)含量;应用黄嘌呤氧化酶法测定超氧化物歧化酶(SOD)的活性;采用Western blotting法检测细胞中Bcl-2和Bax蛋白表达,计算Bax/Bcl-2值。结果:INH可诱导L-02细胞DNA损伤,使细胞线粒体ROS水平、细胞MDA含量及Bax/Bcl-2值明显增高,并使细胞ΔΨm值和SOD活性明显下降。而槲皮素能减轻细胞DNA损伤,减少细胞ROS水平,增加细胞ΔΨm值,降低细胞MDA含量,增加SOD活性,减少Bax/Bcl-2值。结论:INH可通过诱导细胞线粒体氧化应激导致L-02细胞DNA损伤。槲皮素能减轻INH诱导L-02细胞的DNA损伤,对L-02细胞具有保护作用,可能与其抑制ROS介导的线粒体氧化损伤有关。     

天麻素对乙醇诱导肝细胞株L02细胞损伤的影响

目的:探讨天麻素对乙醇诱导肝细胞株L02损伤的影响。方法:将人肝细胞株L02培养,加入不同浓度的乙醇,采用MTT比色法确定乙醇作用的浓度。用流式细胞仪测定细胞活性氧簇(ROS)及线粒体膜电位的改变;采用反相高效液相色谱(RP-HPLC)分析法检测细胞ATP含量。结果:乙醇(25 mL/L)作用36 h可损伤肝细胞,细胞内ROS的水平明显增加;而细胞线粒体膜电位及肝细胞中ATP的含量则显著降低(P0.01)。天麻素具有减轻细胞损伤的作用,并可降低损伤的肝细胞内ROS的含量,增加细胞线粒体膜电位和ATP的水平。结论:天麻素可抑制乙醇诱导的肝细胞损伤及脂质过氧化反应,改善线粒体功能,增加能量合成,发挥保护肝细胞的作用。     

四川新康温石棉通过活性氧/c-Jun氨基末端激酶(ROS/JNK)通路诱导A549细胞凋亡北大核心CSCD

目的研究活性氧/c-Jun氨基末端激酶(ROS/JNK)途径在四川新康温石棉诱导A549人肺上皮细胞凋亡过程的作用。方法采用(12.5、25、50、100、200)μg/m L温石棉作用A549细胞24 h,MTT法检测细胞存活率;设置ROS抑制组,异硫氰酸荧光素标记的膜联素Ⅴ/碘化丙啶(annexinⅤ-FITC/PI)双染色结合流式细胞术检测细胞凋亡、JC-1标记检测线粒体膜电位、二氯二氢荧光黄乙酰乙酯(DCFH-DA)负载检测ROS水平,Western blot法检测磷酸化的c-JNK1(p-JNK1)、p-JNK2、裂解型胱天蛋白酶3(c-caspase-3)蛋白水平。结果随着温石棉剂量增大,细胞存活率下降,温石棉半数抑制剂量为223.43μg/m L;细胞凋亡率呈现剂量-效应关系,胞内ROS水平升高,p-JNK1、p-JNK2、c-caspase-3蛋白水平明显上调,线粒体膜电位降低;与相同剂量温石棉组比较,ROS抑制剂能显著抑制细胞凋亡,降低ROS水平,减少线粒体膜电位的降低程度,并下调p-JNK1、p-JNK2和c-caspase-3蛋白的表达。结论四川新康温石棉可能通过ROS/JNK途径诱导A549细胞发生凋亡。     

小鼠腹腔巨噬细胞凋亡时线粒体的改变及其调控

目的：研究小鼠腹腔巨噬细胞凋亡过程中线粒体和磷酸烟酰胺腺嘌呤（NADPH）氧化酶活性的变化以及信使分子对线粒体膜电位,细胞内活性氧（reactive oxgen species,ORS)和凋亡的影响。方法：激光扫描共聚焦显微术、流术细胞术和荧光标记技术等。结果：1地塞米松诱导巨噬细胞快速凋亡;2例粒体膜电位快速去极化,NADPH氧化酶活性剧降,ROS快速减少,ROS清除剂促进凋亡,3－蛋白激酶C（protein kinaseC,PKC)促进凋亡,ROS急剧减少、线粒体膜去极化;环腺苷酸（cAMP）抑制凋亡、ROS急剧减少,线粒体膜去极化;环鸟苷酸（cGMP),酪氨酸蛋白激酶（TPK）略抑制凋亡,不影响ROS变化,但影响线粒体膜去极化,结论1：地塞米松处理使线粒体内NADPH氧化酶活性剧降,生成ROS迅速减少从而促进巨噬细胞凋亡,2信使分子影响线粒休生成ROS的变化以及线粒体膜去极化从而影响巨噬细胞凋亡,提示线粒体变化,尤其是ROS和膜电位的变化影响巨噬细胞凋亡。     

二烯丙基三硫诱导人髓样白血病HL-60细胞活性氧产生及其细胞毒性作用

目的：探讨二烯丙基三硫(DATS)诱导人白血病HL-60细胞产生活性氧(ROS)及其细胞毒性作用。方法: 用浓度为50、100、150、200 μmol/L DATS处理HL-60细胞1、3、6、12、24 h后，流式细胞计数法检测HL-60细胞内的ROS水平，NBT还原实验分析NADPH氧化酶的活性，分别用NADPH氧化酶特异性阻断剂apocynin与抗氧化剂NAC（N-acetyl-L-cystein）预处理30 min后，观察DATS对HL-60细胞产生活性氧的影响，分光光度法检测细胞质膜氧化产物丙二醛（MDA）与细胞蛋白氧化产物羰基化蛋白（protein carbonyl）。结果: DATS能诱导人白血病HL-60细胞产生ROS，当DATS处理细胞1-3 h 时，HL-60细胞产生ROS随DATS浓度的升高和处理时间的延长而升高，当浓度为150 μmol/L DATS处理细胞3h时，ROS的荧光强度达到最高峰，其后维持在一个较高水平。NADPH氧化酶活性与ROS的产生一致。HL-60细胞的脂质过氧化和羰基化蛋白浓度与DATS诱导ROS产生的趋势基本一致，都在3 h、150 μmol/L处理点达到最高值。应用NADPH氧化酶特异性阻断剂apocynin或抗氧化剂NAC后，能显著降低HL-60细胞ROS的产生和细胞损伤。结论: NADPH氧化酶是DATS诱导 HL-60 细胞产生ROS的主要酶系，ROS能氧化细胞质膜和蛋白质。     

活性氧及能量代谢障碍在体外培养肝细胞脂肪变性中的作用

目的：探讨细胞活性氧（ROS）及线粒体能量代谢障碍在乙醇和小牛血清诱导的体外培养肝细胞脂肪变性中的作用。方法:将人肝细胞株L02进行细胞培养,加入不同浓度的乙醇,采用MTT法确定乙醇作用的最佳浓度；用2%乙醇和50%小牛血清(A+CS)诱导L02细胞，以油红O染色观察细胞内脂滴形成状况,并检测细胞TG的含量；用流式细胞仪（FCM）测定细胞活性氧及线粒体膜电位的改变；采用反相高效液相色谱分析法测定细胞ATP含量。结果:2%乙醇和50%小牛血清作用36 h,肝细胞内有典型的脂滴形成,与对照组相比，细胞内TG含量及ROS水平明显增加；而细胞线粒体膜电位及肝细胞ATP的含量则显著降低(P<0.01)。结论:在乙醇和小牛血清诱导肝细胞脂肪变过程中，细胞ROS的增加及线粒体能量代谢障碍可能发挥了重要的作用。     

紫檀芪激活血红素加氧酶-1减轻小鼠脑缺血再灌注后线粒体氧化损伤

目的:探索紫檀芪(pterostilbene,PTE)对小鼠脑缺血再灌注(IR)后线粒体氧化损伤的作用及可能机制。方法:通过双侧颈总动脉阻断法建立小鼠脑IR模型,腹腔注射PTE或Zn PP(血红素加氧酶-1抑制剂),动物随机均分为IR组、PTE+IR组、PTE+Zn PP+IR组、Zn PP+IR组,并且PTE有2.5 mg/kg、5 mg/kg、10 mg/kg三个剂量组。然后,进行神经功能评分;通过干湿比重法测定脑水肿;火焰光度法测定Na~+含量;Neu N和TUNEL法测定细胞存活和凋亡;通过线粒体膜电位(MMP)、线粒体活性氧(ROS)产物和线粒体复合物I和IV活性测定来检测线粒体的氧化应激损伤;通过Western Blot检测血红素加氧酶-1(HO-1)、NADPH醌氧化还原酶-1(NQO1)、谷胱甘肽S-转移酶(GST)、线粒体和胞浆细胞色素c蛋白的表达。结果:PTE可以提高小鼠的神经功能评分、减轻脑水肿和降低脑Na~+含量。PTE上调HO-1、NQO1和GST的表达,提高MMP、线粒体复合体I/IV活性和线粒体细胞色素c水平,减少线粒体ROS产物和降低胞浆细胞色素c水平,并且有一定的剂量依赖性。但是,PTE的这些作用可以被HO-1的抑制剂Zn PP逆转。结论:在脑IR模型小鼠,PTE通过激活HO-1信号减轻线粒体氧化应激损伤和细胞死亡,从而发挥脑保护作用。     

二苯基碘和夹竹桃麻素通过降低早产儿外周血单个核细胞p47phox位移与水平减少活性氧的产生

目的观察NADPH氧化酶抑制剂二苯基碘(DPI)和夹竹桃麻素(apocynin)对NADPH氧化酶亚基p47phox介导的活性氧(ROS)产生的影响,探讨细胞在高氧条件下,p47phox介导ROS产生的机制。方法 32周以下早产儿,尚未吸氧前取外周血2 m L,分离纯化外周血单个核细胞(PBMC)将所得细胞分为对照组、高氧组、高氧联合DPI处理组、高氧联合apocynin处理组进行培养。对照组置于37℃、50 m L/L的CO2培养箱中,高氧及相应处理组置于950 m L/L的O2与50 m L/L的CO2混合气体中培养48 h。采用Mitosox Red标记结合激光共聚焦显微镜检测PBMC内ROS的生成量、硫代巴比妥酸比色法检测培养液丙二醛含量、免疫荧光检测p47phox在细胞内的定位及移位率、Western blot法检测p47phox的蛋白水平。结果与高氧组相比,其余三组ROS和丙二醛明显减少,p47phox移位率与含量也显著降低;与对照组相比,高氧联合DPI处理组及高氧联合apocynin处理组ROS、丙二醛、p47phox移位率与含量并无显著差异。结论 DPI和apocynin能通过降低p47phox移位与含量来减少高氧诱导的ROS升高。     

雷帕霉素对小鼠星形胶质细胞体外诱导凋亡的影响

目的:探讨雷帕霉素(rapamycin,Rapa)对小鼠星形胶质细胞体外凋亡的影响。方法:无菌分离并体外培养C57BL/6J幼鼠脑组织星形胶质细胞。通过MTT比色法测定并分析Rapa浓度对幼鼠星形胶质细胞存活的影响;SYTOXGreen荧光染色联合荧光酶标仪检测并分析Rapa对H2O2、ionomycin、deferorxamine等诱导剂作用一定时间内细胞存活的影响;Di OC6(3)染色分析Rapa在H2O2氧化应激损伤条件下对星形胶质细胞线粒体膜电势的影响;分别采用H2DCFDA和Mito SOXTMRed荧光染色联合流式细胞术检测Rapa预适应对星形胶质细胞ROS生成以及线粒体内ROS含量的影响。结果:Rapa能促进H2O2以及ionomycin联合deferorxamine损伤作用下的星形胶质细胞的存活,对线粒体膜电势有保护作用,可降低H2O2损伤作用下星形胶质细胞ROS的产生并可以维持胞内线粒体ROS的含量在较低水平。结论:Rapa能够减少细胞内ROS的生成量并降低胞内线粒体内ROS水平;能够减轻H2O2对细胞线粒体膜的损伤破坏,维护线粒体膜电势的稳定性,进而对氧化应激损伤介导细胞凋亡有一定的抑制作用。     

Rapid reactive oxygen species production by mitochondria in endothelial cells exposed to tumor necrosis factor-alpha is mediated by ceramide.

Tumor necrosis factor (TNF)-alpha increases mitochondrial reactive oxygen species (ROS) production in tumor cells and hepatocytes. However, whether TNF-alpha stimulates mitochondrial ROS production in endothelial cells (EC) has not yet been reported. We studied the effect of TNF-alpha on mitochondrial ROS generation in EC and the signaling pathways involved. Cultured human umbilical vein EC (HUVEC) were studied by fluorescence microscopy, using dichlorodihydrofluorescein diacetate (DCFH-DA) as a marker of ROS production and propidium iodide uptake for cell viability. TNF-alpha increased DCFH oxidation in HUVEC dose-dependently. To determine the source of ROS, the mitochondrial respiratory chain inhibitors rotenone + thenoyltrifluoroacetone (TTFA), which inhibit electron entry to ubiquinone, and antimycin A (AA), a blocker of ubisemiquinone, were used. Rotenone and TTFA inhibited (n = 7, P < 0.05), whereas AA increased (118% in 3 min; n = 4, P < 0.01) ROS generation in HUVEC. In contrast, ROS production was not abolished by the nicotinamide adenine dinucleotide phosphate-dependent oxidase inhibitor diphenylene iodonium, by the xanthine oxidase inhibitor allopurinol, nor by the nitric oxide and cyclooxygenase pathway inhibitors N(omega)-nitro-L-arginine and mefenamic acid. In addition, TNF-alpha-induced ROS production was inhibited by the acidic sphingomyelinase inhibitor desipramine (5 microM; -80%, n = 4, P < 0.01) and totally blocked by the ceramide-activated protein kinase (CAPK) inhibitor dimethylaminopurine (1 mM; n = 6, P < 0.05). Thus, TNF-alpha induces mitochondrial ROS production in HUVEC that primarily occurs at the ubisemiquinone site and is mediated by ceramide-dependent signaling pathways involving CAPK.     

Ca2+-dependent generation of mitochondrial reactive oxygen species serves as a signal for poly(ADP-ribose) polymerase-1 activation during glutamate excitotoxicity

Mitochondrial Ca²⁺ uptake and poly(ADP-ribose) polymerase-1 (PARP-1) activation are both required for glutamate-induced excitotoxic neuronal death. Since activation of the glutamate receptors can induce increased levels of reactive oxygen species (ROS), we investigated the relationship of mitochondrial Ca²⁺ uptake and ROS generation, and the possibility that ROS increase is a required signal for PARP-1 activation in cultured striatal neurons. Based on the spatial profile of NMDA-induced ROS generation, we found that only mitochondria showed a significant ROS increase within 30 min after NMDA receptor activation. This ROS increase was inhibited by the mitochondrial complex inhibitors rotenone and oligomycin, but not by the cytosolic phospholipase A₂ or xanthine oxidase inhibitors. Mitochondrial ROS generation was also inhibited by both removal of Ca²⁺ from extracellular medium and blockage of mitochondrial Ca²⁺ uptake by either a mitochondrial uncoupler or a Ca²⁺ uniporter inhibitor. Furthermore, both DNA damage and PARP-1 activation induced by NMDA treatment was inhibited by blocking mitochondrial Ca²⁺ uptake or by antioxidants. Our results demonstrate that ROS production during the early stage of acute excitotoxicity derives primarily from mitochondria and is Ca²⁺-dependent. More importantly, the increase of mitochondrial ROS serves as a signal for PARP-1 activation, suggesting that concomitant mitochondrial Ca²⁺ uptake and PARP-1 activation constitute a unified mechanism for excitotoxic neuronal death.     

Increased production of mitochondrial superoxide in the spinal cord induces pain behaviors in mice: The effect of mitochondrial electron transport complex inhibitors

Scavengers of reactive oxygen species (ROS) have been shown to produce a strong antinociceptive effect on persistent pain, and mitochondria are suggested to be the main source of ROS in the spinal dorsal horn. To explore whether excessive generation of mitochondrial superoxide alone can induce pain, the effect of mitochondrial electron transport complex inhibitors on the development of mechanical hyperalgesia was examined in mice. Intrathecal injection of an electron transport complex inhibitor, antimycin A or rotenone, in normal mice resulted in a slowly developing but long-lasting and dose-dependent mechanical hyperalgesia. The levels of mechanical hyperalgesia after antimycin A, a complex III inhibitor, were higher than that with rotenone, a complex I inhibitor. A large increase of mitochondrial superoxide in the spinal dorsal horn and a strong antinociceptive effect of ROS scavengers, phenyl-N-tert-butylnitrone (PBN) and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) were observed in antimycin A-treated mice. The study indicates that the enhanced production of spinal mitochondrial superoxide alone without nerve injury can produce mechanical hyperalgesia.     

Oxidation of plasma cysteine/cystine redox state in endotoxin-induced lung injury

Several lines of evidence indicate that perturbations in the extracellular thiol/disulfide redox environment correlate with the progression and severity of acute lung injury (ALI). Cysteine (Cys) and its disulfide Cystine (CySS) constitute the most abundant, low-molecular-weight thiol/disulfide redox couple in the plasma, and Cys homeostasis is adversely affected during the inflammatory response to infection and injury. While much emphasis has been placed on glutathione (GSH) and glutathione disulfide (GSSG), little is known about the regulation of the Cys/CySS couple in ALI. The purpose of the present study was to determine whether endotoxin administration causes a decrease in Cys and/or an oxidation of the plasma Cys/CySS redox state (E(h) Cys/CySS), and to determine whether these changes were associated with changes in plasma E(h) GSH/GSSG. Mice received endotoxin intraperitoneally, and GSH and Cys redox states were measured at time points known to correlate with the progression of endotoxin-induced lung injury. E(h) in mV was calculated using Cys, CySS, GSH, and GSSG values by high-performance liquid chromatography and the Nernst equation. We observed distinct effects of endotoxin on the GSH and Cys redox systems during the acute phase; plasma E(h) Cys/CySS was selectively oxidized early in response to endotoxin, while E(h) GSH/GSSG remained unchanged. Unexpectedly, subsequent oxidation of E(h) GSH/GSSG and E(h) Cys/CySS occurred as a consequence of endotoxin-induced anorexia. Taken together, the results indicate that enhanced oxidation of Cys, altered transport of Cys and CySS, and decreased food intake each contribute to the oxidation of plasma Cys/CySS redox state in endotoxemia.     

The effect of mitochondrial inhibitors on membrane currents in isolated neonatal rat carotid body type I cells

Inhibitors of mitochondrial energy metabolism have long been known to be potent stimulants of the carotid body, yet their mechanism of action remains obscure. We have therefore investigated the effects of rotenone, myxothiazol, antimycin A, cyanide (CN⁻) and oligomycin on isolated carotid body type I cells. All five compounds caused a rapid rise in intracellular Ca²⁺, which was inhibited on removal of extracellular Ca²⁺. Under current clamp conditions rotenone and CN⁻ caused a rapid membrane depolarization and elevation of [Ca²⁺]_i. Voltage clamping cells to −70 mV substantially attenuated this rise in [Ca²⁺]_i. Rotenone, cyanide, myxothiazol and oligomycin significantly inhibited resting background K⁺ currents. Thus rotenone, myxothiazol, cyanide and oligomycin mimic the effects of hypoxia in that they all inhibit background K⁺ current leading to membrane depolarization and voltage-gated calcium entry. Hypoxia, however, failed to have any additional effect upon membrane currents in the presence of CN⁻ or rotenone or the mitochondrial uncoupler p -trifluoromethoxyphenyl hydrazone (FCCP). Thus not only do mitochondrial inhibitors mimic the effects of hypoxia, but they also abolish oxygen sensitivity. These observations suggest that there is a close link between oxygen sensing and mitochondrial function in type I cells. Mechanisms that could account for this link and the actions of mitochondrial inhibitors are discussed.     

A rotenone-sensitive site and H2O2 are key components of hypoxia-sensing in neonatal rat adrenomedullary chromaffin cells

In the perinatal period, adrenomedullary chromaffin cells (AMC) directly sense PO2 and secrete catecholamines during hypoxic stress, and this response is lost in juvenile ( approximately 2 week-old) chromaffin cells following postnatal innervation. Here we tested the hypothesis that a rotenone-sensitive O2-sensor and ROS are involved in the hypoxic response of AMC cultured from neonatal and juvenile rats. In whole-cell recordings, hypoxia (PO2=5-15 mm Hg) inhibited outward current in neonatal AMC; this response was reversed by exogenous H2O2 and mimicked and occluded by intracellular catalase (1000 units/ml), as well as the antioxidants, N-acetyl-L-cysteine (NAC; 50 microM) and Trolox (200 microM). Acute hypoxia decreased ROS levels and stimulated ATP secretion in these cells, as measured by luminol and luciferin-luciferase chemiluminescence, respectively. Of several mitochondrial electron transport chain (ETC) inhibitors tested, only rotenone, a complex I blocker, mimicked and occluded the effects of hypoxia on outward current, cellular ROS, and ATP secretion. Succinate donors, which act as complex II substrates, reversed the effects of hypoxia and rotenone in neonatal AMC. In contrast, in hypoxia-insensitive juvenile AMC, neither NAC nor rotenone stimulated ATP secretion though they both caused a decrease in ROS levels. We propose that O2-sensing by neonatal AMC is mediated by decreased ROS generation via a rotenone-sensitive site that is coupled to outward current inhibition and secretion. Interestingly, juvenile AMC display at least two modifications, i.e. an uncoupling of the O2-sensor from ROS regulation, and an apparent insensitivity of outward current to decreased ROS.     

Differentiation-specific effects of LHON mutations introduced into neuronal NT2 cells

Inheritance of one of three primary mutations at positions 11778, 3460 or 14484 of the mitochondrial genome in subunits of Complex I causes Leber's Hereditary Optic Neuropathy (LHON), a specific degeneration of the optic nerve, resulting in bilateral blindness. It has been unclear why inheritance of a systemic mitochondrial mutation would result in a specific neurodegeneration. To address the neuron-specific degenerative phenotype of the LHON genotype, we have created cybrids using a neuronal precursor cell line, Ntera 2/D1 (NT2), containing mitochondria from patient lymphoblasts bearing the most common LHON mutation (11778) and the most severe LHON mutation (3460). The undifferentiated LHON-NT2 mutant cells were not significantly different from the parental cell control in terms of mtDNA/nDNA ratio, mitochondrial membrane potential, reactive oxygen species (ROS) production or the ability to reduce Alamar Blue. Differentiation of NT2s resulted in a neuronal morphology and neuron-specific pattern of gene expression, and a 3-fold reduction in mtDNA/nDNA ratio in both mutant and control cells; however, the differentiation protocol yielded significantly less LHON cells than controls, by 30%, indicating either a decreased proliferative potential or increased cell death of the LHON-NT2 cells. Differentiation of the cells to the neuronal form also resulted in significant increases in ROS production in the LHON-NT2 neurons versus controls, which is abolished by rotenone, a specific inhibitor of Complex I. We infer that the LHON genotype requires a differentiated neuronal environment in order to induce increased mitochondrial ROS, which may be the cause of the reduced NT2 yield; and suggest that the LHON degenerative phenotype may be the result of an increase in mitochondrial superoxide which is caused by the LHON mutations, possibly mediated through neuron-specific alterations in Complex I structure.     

胆固醇通过NADPH氧化酶诱导ROS升高,NF-κB活化进而导致内皮细胞损伤

目的:研究胆固醇对人脐静脉内皮细胞(HUVECs)的损伤是否与细胞内活性氧(ROS)升高有关,明确此种情况下ROS的主要来源。方法:体外培养HUVECs-12,设置正常对照组、溶媒(无水乙醇)组、胆固醇组、N-乙酰半胱氨酸(NAC)作用1 h后再加入胆固醇作用48 h组。以DCFH-DA为荧光探针,流式细胞术检测细胞内ROS水平;免疫细胞化学方法检测细胞内核因子-κB亚单位p65核移位阳性细胞数;分别用比色法、硝酸酶还原法及ELISA检测细胞培养液中乳酸脱氢酶(LDH)活性、一氧化氮(NO)及单核细胞趋化蛋白-1(MCP-1)浓度。并观察加入产生ROS的4种酶抑制剂二联苯碘(DPI)、鱼藤酮(rotenone)、奥苷嘌醇(oxypurinol)、N-硝基-L-精氨酸甲酯(L-NAME)后细胞内ROS水平。结果:(1)与正常对照组比较,50 mg/L胆固醇能升高细胞内ROS(P0.01),并能激活细胞内NF-κB p65的核移位(P0.01),升高细胞培养液中LDH活性、MCP-1浓度,降低NO浓度(P0.01);(2)与胆固醇作用组相比,NADPH氧化酶抑制剂DPI预作用组细胞内ROS明显降低(P0.01),retenone也可以部分抑制ROS的产生(P0.05),oxypurinol和L-NAME预作用则几乎不影响胆固醇所致的ROS生成增加(P0.05)。结论:一定浓度的游离胆固醇能引起内皮细胞内ROS升高,激活细胞内NF-κB,进而导致内皮细胞损伤;此情况下细胞内产生的ROS主要来源于NADPH氧化酶。     

Effects of mitochondrial poisons on glutathione redox potential and carotid body chemoreceptor activity

Low oxygen sensing in chemoreceptor cells involves the inhibition of specific plasma membrane K(+) channels, suggesting that mitochondria-derived reactive oxygen species (ROS) link hypoxia to K(+) channel inhibition, subsequent cell depolarization and activation of neurotransmitter release. We have used several mitochondrial poisons, alone and in combination with the antioxidant N-acetylcysteine (NAC), and quantify their capacity to alter GSH/GSSG levels and glutathione redox potential (E(GSH)) in rat diaphragm. Selected concentrations of mitochondrial poisons with or without NAC were tested for their capacity to activate neurotransmitter release in chemoreceptor cells and to alter ATP levels in intact rat carotid body (CB). We found that rotenone (1 microM), antimycin A (0.2 microg/ml) and sodium azide (5mM) decreased E(GSH); NAC restored E(GSH) to control values. At those concentrations mitochondrial poisons activated neurotransmitter release from CB chemoreceptor cells and decreased CB ATP levels, NAC being ineffective to modify these responses. Additional experiments with 3-nitroprionate (5mM), lower concentrations of rotenone and dinitrophenol revealed variable relationships between E(GSH) and chemoreceptor cell neurotransmitter release responses and ATP levels. These findings indicate a lack of correlation between mitochondrial-generated modifications of E(GSH) and chemoreceptor cells activity. This lack of correlation renders unlikely that alteration of mitochondrial production of ROS is the physiological pathway chemoreceptor cells use to signal hypoxia.